Wheeled vehicles, including skateboards, scooters and other conveyances upon which a user stands, may go out of control for a number of reasons, including the unbridled momentum of both rider and the vehicle. The rider could benefit from speed control, but there are no commercially available controls which are durable, functional, or stable and which don't burden the vehicle or rider with structure which detracts significantly from performance of the vehicle.
Especially with skateboards, the user needs to be able to keep hands free for balance. Any mechanism which would require hand manipulation would seriously impede the ability of the user to balance on the skateboard and may even impede the ability to steer it. Another problem is proportionality of control. Where a control might be manual, perhaps with cable control to the skateboard wheels, it relies upon the user's manual sensitivity to avoid over controlling the speed. A sudden reaction to a condition which might cause flinching in the hand could produce an accident. A cable or remotely manual controlled speed control will not be self-mitigating.
No commercially available remotely controlled speed control possesses all of the needed characteristics for a skateboard system, including proportional control, a control not significantly subject to accidental or unintentional actuation, and a control with self mitigating mechanism components to prevent jamming, and wear reduction structures combined with the ability to adequately control speed. Because skateboards operate in a harsh environment, the needed isolation of a speed control from the negative debris is also not found. Isolation is not found with regard to a range of debris damage from that which may wear the system down rapidly, to that which could jam the wheel rotation abruptly. Toughness and durability is another factor lacking in any commercially available speed controls, and especially in the case of a skateboard which operates in a severe environment. Skateboarders will not tolerate any mechanical system which breaks down easily or which cannot tolerate the harsh skateboarding environment.